Improve Sendable checking for server code (#1605)

Motivation:

The server handler protocol must be Sendable so that any methods on the
handler are also Sendable as annotating methods as `@Sendable` does not
work as expected. It follows from this that generated server interceptor
factories must also be Sendable (they already are for clients). This
puts the `ServerInterceptor` class in an awkward position: it must be
Sendable but is not inherently thread-safe (these restrictions are
documented and existed before Sendable checking was introduced to
Swift). The `ClientInterceptor` has the same restrictions and is
`@unchecked Sendable` so we elect to do the same for the
`ServerInterceptor`.

Modifications:

- Make generated server handlers and server interceptor factories Sendable
- Make `ServerInterceptor` `@unchecked Sendable`
- Regenerate
- Fix some warnings in test code

Result:

Better Sendable checking

Author: glbrntt

Sources/Examples/Echo/Model/echo.grpc.swift

@@ -613,31 +613,31 @@ extension Echo_EchoProvider {
 
 /// To implement a server, implement an object which conforms to this protocol.
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
-public protocol Echo_EchoAsyncProvider: CallHandlerProvider {
+public protocol Echo_EchoAsyncProvider: CallHandlerProvider, Sendable {
   static var serviceDescriptor: GRPCServiceDescriptor { get }
   var interceptors: Echo_EchoServerInterceptorFactoryProtocol? { get }
 
   /// Immediately returns an echo of a request.
-  @Sendable func get(
+  func get(
     request: Echo_EchoRequest,
     context: GRPCAsyncServerCallContext
   ) async throws -> Echo_EchoResponse
 
   /// Splits a request into words and returns each word in a stream of messages.
-  @Sendable func expand(
+  func expand(
     request: Echo_EchoRequest,
     responseStream: GRPCAsyncResponseStreamWriter<Echo_EchoResponse>,
     context: GRPCAsyncServerCallContext
   ) async throws
 
   /// Collects a stream of messages and returns them concatenated when the caller closes.
-  @Sendable func collect(
+  func collect(
     requestStream: GRPCAsyncRequestStream<Echo_EchoRequest>,
     context: GRPCAsyncServerCallContext
   ) async throws -> Echo_EchoResponse
 
   /// Streams back messages as they are received in an input stream.
-  @Sendable func update(
+  func update(
     requestStream: GRPCAsyncRequestStream<Echo_EchoRequest>,
     responseStream: GRPCAsyncResponseStreamWriter<Echo_EchoResponse>,
     context: GRPCAsyncServerCallContext
@@ -669,7 +669,7 @@ extension Echo_EchoAsyncProvider {
         requestDeserializer: ProtobufDeserializer<Echo_EchoRequest>(),
         responseSerializer: ProtobufSerializer<Echo_EchoResponse>(),
         interceptors: self.interceptors?.makeGetInterceptors() ?? [],
-        wrapping: self.get(request:context:)
+        wrapping: { try await self.get(request: $0, context: $1) }
       )
 
     case "Expand":
@@ -678,7 +678,7 @@ extension Echo_EchoAsyncProvider {
         requestDeserializer: ProtobufDeserializer<Echo_EchoRequest>(),
         responseSerializer: ProtobufSerializer<Echo_EchoResponse>(),
         interceptors: self.interceptors?.makeExpandInterceptors() ?? [],
-        wrapping: self.expand(request:responseStream:context:)
+        wrapping: { try await self.expand(request: $0, responseStream: $1, context: $2) }
       )
 
     case "Collect":
@@ -687,7 +687,7 @@ extension Echo_EchoAsyncProvider {
         requestDeserializer: ProtobufDeserializer<Echo_EchoRequest>(),
         responseSerializer: ProtobufSerializer<Echo_EchoResponse>(),
         interceptors: self.interceptors?.makeCollectInterceptors() ?? [],
-        wrapping: self.collect(requestStream:context:)
+        wrapping: { try await self.collect(requestStream: $0, context: $1) }
       )
 
     case "Update":
@@ -696,7 +696,7 @@ extension Echo_EchoAsyncProvider {
         requestDeserializer: ProtobufDeserializer<Echo_EchoRequest>(),
         responseSerializer: ProtobufSerializer<Echo_EchoResponse>(),
         interceptors: self.interceptors?.makeUpdateInterceptors() ?? [],
-        wrapping: self.update(requestStream:responseStream:context:)
+        wrapping: { try await self.update(requestStream: $0, responseStream: $1, context: $2) }
       )
 
     default:
@@ -705,7 +705,7 @@ extension Echo_EchoAsyncProvider {
   }
 }
 
-public protocol Echo_EchoServerInterceptorFactoryProtocol {
+public protocol Echo_EchoServerInterceptorFactoryProtocol: Sendable {
 
   /// - Returns: Interceptors to use when handling 'get'.
   ///   Defaults to calling `self.makeInterceptors()`.

Sources/Examples/HelloWorld/Model/helloworld.grpc.swift

@@ -252,12 +252,12 @@ extension Helloworld_GreeterProvider {
 ///
 /// To implement a server, implement an object which conforms to this protocol.
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
-public protocol Helloworld_GreeterAsyncProvider: CallHandlerProvider {
+public protocol Helloworld_GreeterAsyncProvider: CallHandlerProvider, Sendable {
   static var serviceDescriptor: GRPCServiceDescriptor { get }
   var interceptors: Helloworld_GreeterServerInterceptorFactoryProtocol? { get }
 
   /// Sends a greeting.
-  @Sendable func sayHello(
+  func sayHello(
     request: Helloworld_HelloRequest,
     context: GRPCAsyncServerCallContext
   ) async throws -> Helloworld_HelloReply
@@ -288,7 +288,7 @@ extension Helloworld_GreeterAsyncProvider {
         requestDeserializer: ProtobufDeserializer<Helloworld_HelloRequest>(),
         responseSerializer: ProtobufSerializer<Helloworld_HelloReply>(),
         interceptors: self.interceptors?.makeSayHelloInterceptors() ?? [],
-        wrapping: self.sayHello(request:context:)
+        wrapping: { try await self.sayHello(request: $0, context: $1) }
       )
 
     default:
@@ -297,7 +297,7 @@ extension Helloworld_GreeterAsyncProvider {
   }
 }
 
-public protocol Helloworld_GreeterServerInterceptorFactoryProtocol {
+public protocol Helloworld_GreeterServerInterceptorFactoryProtocol: Sendable {
 
   /// - Returns: Interceptors to use when handling 'sayHello'.
   ///   Defaults to calling `self.makeInterceptors()`.

Sources/Examples/RouteGuide/Model/route_guide.grpc.swift

@@ -530,7 +530,7 @@ extension Routeguide_RouteGuideProvider {
 ///
 /// To implement a server, implement an object which conforms to this protocol.
 @available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
-public protocol Routeguide_RouteGuideAsyncProvider: CallHandlerProvider {
+public protocol Routeguide_RouteGuideAsyncProvider: CallHandlerProvider, Sendable {
   static var serviceDescriptor: GRPCServiceDescriptor { get }
   var interceptors: Routeguide_RouteGuideServerInterceptorFactoryProtocol? { get }
 
@@ -540,7 +540,7 @@ public protocol Routeguide_RouteGuideAsyncProvider: CallHandlerProvider {
   ///
   /// A feature with an empty name is returned if there's no feature at the given
   /// position.
-  @Sendable func getFeature(
+  func getFeature(
     request: Routeguide_Point,
     context: GRPCAsyncServerCallContext
   ) async throws -> Routeguide_Feature
@@ -551,7 +551,7 @@ public protocol Routeguide_RouteGuideAsyncProvider: CallHandlerProvider {
   /// streamed rather than returned at once (e.g. in a response message with a
   /// repeated field), as the rectangle may cover a large area and contain a
   /// huge number of features.
-  @Sendable func listFeatures(
+  func listFeatures(
     request: Routeguide_Rectangle,
     responseStream: GRPCAsyncResponseStreamWriter<Routeguide_Feature>,
     context: GRPCAsyncServerCallContext
@@ -561,7 +561,7 @@ public protocol Routeguide_RouteGuideAsyncProvider: CallHandlerProvider {
   ///
   /// Accepts a stream of Points on a route being traversed, returning a
   /// RouteSummary when traversal is completed.
-  @Sendable func recordRoute(
+  func recordRoute(
     requestStream: GRPCAsyncRequestStream<Routeguide_Point>,
     context: GRPCAsyncServerCallContext
   ) async throws -> Routeguide_RouteSummary
@@ -570,7 +570,7 @@ public protocol Routeguide_RouteGuideAsyncProvider: CallHandlerProvider {
   ///
   /// Accepts a stream of RouteNotes sent while a route is being traversed,
   /// while receiving other RouteNotes (e.g. from other users).
-  @Sendable func routeChat(
+  func routeChat(
     requestStream: GRPCAsyncRequestStream<Routeguide_RouteNote>,
     responseStream: GRPCAsyncResponseStreamWriter<Routeguide_RouteNote>,
     context: GRPCAsyncServerCallContext
@@ -602,7 +602,7 @@ extension Routeguide_RouteGuideAsyncProvider {
         requestDeserializer: ProtobufDeserializer<Routeguide_Point>(),
         responseSerializer: ProtobufSerializer<Routeguide_Feature>(),
         interceptors: self.interceptors?.makeGetFeatureInterceptors() ?? [],
-        wrapping: self.getFeature(request:context:)
+        wrapping: { try await self.getFeature(request: $0, context: $1) }
       )
 
     case "ListFeatures":
@@ -611,7 +611,7 @@ extension Routeguide_RouteGuideAsyncProvider {
         requestDeserializer: ProtobufDeserializer<Routeguide_Rectangle>(),
         responseSerializer: ProtobufSerializer<Routeguide_Feature>(),
         interceptors: self.interceptors?.makeListFeaturesInterceptors() ?? [],
-        wrapping: self.listFeatures(request:responseStream:context:)
+        wrapping: { try await self.listFeatures(request: $0, responseStream: $1, context: $2) }
       )
 
     case "RecordRoute":
@@ -620,7 +620,7 @@ extension Routeguide_RouteGuideAsyncProvider {
         requestDeserializer: ProtobufDeserializer<Routeguide_Point>(),
         responseSerializer: ProtobufSerializer<Routeguide_RouteSummary>(),
         interceptors: self.interceptors?.makeRecordRouteInterceptors() ?? [],
-        wrapping: self.recordRoute(requestStream:context:)
+        wrapping: { try await self.recordRoute(requestStream: $0, context: $1) }
       )
 
     case "RouteChat":
@@ -629,7 +629,7 @@ extension Routeguide_RouteGuideAsyncProvider {
         requestDeserializer: ProtobufDeserializer<Routeguide_RouteNote>(),
         responseSerializer: ProtobufSerializer<Routeguide_RouteNote>(),
         interceptors: self.interceptors?.makeRouteChatInterceptors() ?? [],
-        wrapping: self.routeChat(requestStream:responseStream:context:)
+        wrapping: { try await self.routeChat(requestStream: $0, responseStream: $1, context: $2) }
       )
 
     default:
@@ -638,7 +638,7 @@ extension Routeguide_RouteGuideAsyncProvider {
   }
 }
 
-public protocol Routeguide_RouteGuideServerInterceptorFactoryProtocol {
+public protocol Routeguide_RouteGuideServerInterceptorFactoryProtocol: Sendable {
 
   /// - Returns: Interceptors to use when handling 'getFeature'.
   ///   Defaults to calling `self.makeInterceptors()`.

Sources/GRPC/Interceptor/ServerInterceptors.swift

@@ -42,7 +42,7 @@ import NIOCore
 /// require any extra attention. However, if work is done on a `DispatchQueue` or _other_
 /// `EventLoop` then implementers should ensure that they use `context` from the correct
 /// `EventLoop`.
-open class ServerInterceptor<Request, Response> {
+open class ServerInterceptor<Request, Response>: @unchecked Sendable {
   public init() {}
 
   /// Called when the interceptor has received a request part to handle.